Process of producing aromatic hydrocarbons



, carbon nucleus, may e UNITED STATES PATENT OFFICE.

ALEXANDEES. BAIAGE, OI DETMITyKIOHIGAN, ASSIGNOB T0 BOSTAPH ENGINEER. ING CORPORATION, OF DETROIT, MICHIGAILIA CORPORATION OF NEW YORK.

O1 PRODUCING ABOMATIC HYDROCABBONS.

No Drawing.

To all whom it may concern:

Be it known that 1 ALEXANDER S. RAM- AGE a citizen of the United States, residing at betroit, in, the county of Wayne an State of Michi an, have invented certain new and useful mprovements in Processes of Producin Aromatic Hydrocarbons, of which the 0 lowing is a specification.

This invention is a process whereby aromatic hydrocarbons, especially such as contain a sidechain or on attached to the into other aromatic hydrocarbons which are usually simpler in constitution owing to the replacement by :hydrogen of one or more of the. side chains or groups. The process involves the hydrogenation of the aromaticv hydrocarbon at an elevated temperature in presence of a catalyst, which in the referred embodiment of the invention is a lower oxid of iron, or such mixtures of lower oxids as are prepared by the reduction of' ferric oxid.

While the invention is applicable to the treatment of a rather wide range of aromatic' hydrocarbons, I' will describe it byway of example in its specific application to the trans ormation of those aromatic bodies which exist in so-called solvent naphtha, comprising chiefly xylene, its hi her homologues, cumene, etc., and closely re ated bodies. I have found that under suitable conditions it is possible to effect adirect reduction (hydrogenation) of these hydrocarbons, whereby the alkyl group (meth l, ethyl, etc.) is replaced by'hydron, t ereby enriching the nucleus in hyi ogen. As a typical example of my process I may refer to the transformation of xylene into toluene, the conversion probably occurring in the manner indicated by the following equation.

0.11.0115 011.. Toluene Methane Hydrogen I A further transformation of the samegeneral character would involve the conversion of toluene into benzene:

and inthe practice of the invention is usually found that the product consists of Specification of Letters Patent.

irectly converted Patented Jan. 18, 1921.

Application ma June 24, 1918. Serial No. 241,044.

.tion from the original starting materiaL- In case the material originall treated is solvent naphtha, the cyclic hy rocarbons which predominate in the and toluene.

The catalyst which I prefer to use is a product are benzene I lower oxid of iron, or a mixture of such lower oxids, conveniently prepared by heating ferric oxid in a current of hydrogen or other reducing gas whlle avoiding reduction to metallic iron. Any suitable catalyst for hydrogenation, including nickel, may

however be used without departing from my invention.

The invention will now be described 1b reference to a specific embodiment thereof: 1t being of course understood that it is not limited to the treatment. of the particularraw material mentioned, nor to the manipulative details described, nor to the use of any particular type of apparatus.

Ewample.

The conversion apparatus consisted of an iron pipe approximately twenty feet in length by about three inches in internal diameter. This was mounted at a slight inclination to the horizontal, and was initiallyv 'course be used, or if desired the hydrocarbons may be vaporized in an external retort orfstill. Thefapparatus used forms no part of the present invention.

The ferric oxid was first reduced to a lower state of oxidation by passing a current of hydrogen through the heated contents of the ipe. Thereafter solvent naphtha was fed F1 gal. per hr.) directly to the upper end of the pipe and vaporized. in contact with the iron oxid therein. The V9. rs traversed the heated contents of the pipe, and were subjected, at the outlet end, to the appropriate recovery operations including condensaa... in a refrigerated-coil, and scrubbing the exit gases, first with the collected condensate and then with wash oil, such as is used in benzole recovery plants. The scrubbed exit 'gases' were collected in a gasometer. Hy-

drogen in some excess of the actual reaction requlrements was continuously mtroduced into the reaction pipe. The pressures used were slightly above atmospheric, being sufiicient only to secure a regular movement of the gases through the reaction tube and scrubbing system. The temperature in the tube beyond the vaporizing section was held substantially constant throughout the opera-- tion, the pyrometer readings in two success1ve 730' The hydrogen was supplied to the above tube at the rate of approximately .25

pounds per hour.

Under. these specific conditions approximately 75% of the original solvent naphtha escaped hydrogenation, and was recovered in'the fractionation of the mixed product and returned to the reaction, tube for re treatment. The balance, or converted fraction, was found to contain in two successiverun's, 36.46 and 33.10% of a light fraction,

I chiefly benzene, mixed with some low-boil- The percentage of material-undergoing con- 1 i I ing naphthenes; and 60.15 and 65.37% of toluene. The totalrecovery ineach case was m' excess of 95% ofthe original material.

oaerationsbeing respectively 700 and version depends ofcourse primarily upon the length of the tube, or thenumber of tubes operating in series, and may be increased as desired; in other words, the provision of additional tube length is equivalent from an operating point of view to returning the unconverted fraction to the original tube. I claim 1. Process of treatin aromatic bodies con-.

taining .one or more a 1 groups, comprismg replacing an alkyl group by hydrogen,

-- by subgecting the aromatic body to the action of h rogen at a temperature approximatmg 00 0., in presence of a catalyst comprisirlg a lower oxid of iron.

recess of treating aromatic bodies containing a plurality of alkyl groups, comprismg replacing an alkyl group by hydrogen, by sub ecting the aromatle body to the action 7 of hydrogen at a temperature approximating of xylene by hydrogen, by subjecting xylene to the action of hydrogen at a temperature approximating 700 (3., in presence of a catalyst comprising a loweroxld of iron.

In testimony whereof, I. afiix my signa- 'ture.

' s aman. 

